Nb1-Zr dual active sites constructed on ZrO2 boost nitrite-to-ammonia electroreduction

Electrochemical nitrite-to-ammonia reduction offers a promising avenue for wastewater treatment and sustainable electrosynthesis of NH3. In this study, we immobilize Nb single atoms on a ZrO2 substrate (Nb1–ZrO2) as an efficient NO2RR catalyst. It is demonstrated that the created Nb1-Zr dual sites on Nb1-ZrO2 enhance the adsorption and activation of NO2, optimize the adsorption of key·NH3 intermediate to lower the reaction energy barrier, resulting in an overall enhancement of the NO2RR activity. Remarkably, by assembling Nb1-ZrO2 in a flow cell, we achieve the maximum FENH3 of 95.87 % and NH3 yield rate of 1588.78 µmol h−1cm−2 at a high current density of 263.59 mA cm−2, as well as the stable operation of 100 h, performing among the best of reported NO2RR electrocatalysts.